Thermostatic control



Sept. 11, 1934. w H. SHAW 1,972,908

THERMOSTATIC CONTROL Filed Dec. 25, 1933 INVENTOR. W/fi/fl 77. J%azy BYn p w fi% ATTORNEYJI' Patented'sept. 11 1934 UNITED STATES PATENT OFFICEApplication December 23, 1933, Serial No. 703,709 4 Claims. (Cl. 23693)The present invention relates to a thermostatic means for automaticallycontrolling the fuel feed to an internal combustion engine. Moreparticularly, the invention contemplates the provision of an orificeadjustable in size whereby the ratio of vaporized fuel to the air intakewill be decreased in direct proportion to the temperature of operationof the internal combustion engine.

The ratio of fuel to air in such anengine is commonly referred to as themixture. well known that a rich mixture is required for an internalcombustion engine operating under.

relatively low temperature conditions; and corre-. 'spondingly, that alean mixture will suffice for higher temperature conditions.Accordingly, it is a general object and nature of my invention toprovide a temperature responsive .means which will so vary either theamount of vaporized fuel or the amount of air which is induced in anengine, in a manner directly, dependent upontemperature conditions. Theadvantage of such a thermostatic control should be apparent, in that theinternal combustion engineis permitted to operate at a higherefficiency, and excess va-;

porized fuel which is induced into the engine at higher temperatureconditions is not wasted due to incomplete combustion.

Another object of the invention is to provide snap-action thermostaticcontrol. In this modified form of the invention, the change in the sizeof the orifice ismade abruptly and suddenly, as distinguished from agradual varia-- tion in the effective orifice area. In other words,

, the change in orifice size in this last-mentioned,

form of construction will occur entirely .at-a single predeterminedtemperature rather than throughout a temperature range.

A further object of the invention is to provide such a thermostaticcontrol means which readily [lends itself to an economy of manufacture.Another object is toprovide a valve togetherwith a plurality ofbi-metallic thermally re-' and" sponsive discs which maybe easily,cheaply v operatively assembled as a complete unit. Still another objectis to so design such a completely assembled unit whereby the movingparts such as the bi-metallic discs and the valve stem are protectedfrom the interference and injurious effect caused by the ingress of dirtand foreign particles. shall become apparent as the followingdescription proceeds.

To the accomplishment of the foregoing an It is.

Additional objects and advantages related ends, said invention, then,consists of the means hereinafter fully described and particularlypointed out in the claims.

The annexed drawing and the following description set forth in detailcertain mechanism embodying the invention, such disclosed meansconstituting, however, but. one of various mechanical forms in which theprinciple of the invention may be used.

In said annexed drawing:

Fig.- 1 is a section view showing the thermostatic control meansconstructed according to the principle of my invention as applied to thefuel feed orifice of the carburetor of an internal combustion engine;Fig. 2 is a sectional view of an alternative form of construction inwhich theprinciple of my. invention is incorporated in an air bleederfor the intake manifold of an internal combustion engine; Fig. 3 is anelevational view. showing the automatic bleeder of Fig. 2, in positionon the intake manifold; Fig.- 4 .is a sectional View of another modifiedform of construction which may be substituted for the-form shown in Fig.l and which is intended to possess. the above-mentioned snap-action.mode of operation.

Now referring more particularly to the draw ing, in Fig. 1 thereis showna portion of a carburetor housing or casing indicated generally by thenumeral 1. A liquid fuel conduit 2 is connected by means of the openings3 to the orifice 4. -A tapered or cone-shaped needle valve 5 extendsthrough the orifice 4 and for a short distance up into the intakepassage 6.

Longitudinal movement of the needle valve 5 with respect to the orifice4 will, of course, result in-a variation of the effectivesize ofsuch'orifice. The 'lowerendof the needle valve 5 is movably supported ina housing member 7. Between the enlarged lower end- 8,0f the needlevalve 5 and theinnerwall of the housing 7 there is positionedthe-.coiled spring .9. A plurality of bi-metallic discs 10 arelocated incontact with the end of the enlarged portion 8 and are held in positionby means of the-cap 11.which threadably engages with the inner wall ofthe housing '7. l

I The exterior of the housing 7 is threadably engaged as at 12 to thecarburetor housing 1. An annular milled cap 132is provided on the lowerend of the housing 7. Asmall resilient finger 14 is adapted to engage inthe grooves in the milled cap '13. I It will thus be seen that the cap13 .may be manipulated to vary the vertical position of the housing. 7with respect to the carburetor .casingl, and incidentally to regulate aposition of the needle valve 5 with respect to the orifice 4. Theresilient finger 14 functions as a detent for holding the cap 13 andhousing 7 against rotation. A rectangular slot 15 is provided in theouter'side of the cap 11 for the insertion of a manipulating tool suchas a screw driver.

The operation of the above described device is as follows: I, v

Under relatively low. temperature conditions, the bi-metallic discs 10will assume afiattened condition. The action of the compression spring 9will tend to force the valve stem 5 downwardly with respect to theorifice 4, thereby enlarging the effective size of the latter. Upon anincrease in temperature, the bi-metallic discslO will com-- mence tobend or assume a dished conformation somewhat as shown in Fig.1. Suchdeflection of the bi-metallic discs 10 will then overcome the force ofthe spring 9 and thereby urge the needle valve-'5 in an upward directionwith the result that the effective size of-the orifice 4 will bedecreased. Thus the amount offuel which isdrawn in'through the intakepassage 6 is gradually decreased in direct proportion to temperatureincreases, and a fuel mixture varying from rich to lean iscorrespondingly supplied to the engine as the temperature of operationrises.

As shown in Figs. 2 and 3,'the principle of my invention may. also beutilized and incorporated in a slightly modified form of design for thepurpose of varying the amount of air which is induced into the engine.In this instance, a thermostatic control means takes the form of ableeder attached to the intake manifold 20. The bleeder consists' ofahousing member 21 which is attached. by means of the threaded portion22 to the wall of the manifold 20. An orifice 23 is 40 placed incommunication with the atmosphere by means of. the passages 24 in thehousing 21. A valve 25 is movably mounted and supported in the housing21. The lower end of the valve is enlarged as at 26 for the purpose ofclosing the orifice 23. The upper end of the valve 25 is laterallyflanged as at 27 and a spring 28 is positioned between the fiange 27 andthe inner wall of the housing 21. A plurality of bi-metallic discs 29contact the upper surface of the flange 2'7 and are also in contact withand held in position by means of the threaded cap member 30. The cap 30engages with the inner-walls of the housing .21 by means of the threads31. A rec tangular slot 32 is provided in the outersurface of the cap 30for. the reception of a manipulating tool suchv as'a screwdriven- Theoperation of the. last described "form of construction is subsantiallyanalogous to that set forth in -connection withthe structure showninFig. 1.

The forceof the spring 28 is made greater than theefiective force of themaximum vacuum pressure, which is exerted on the surface of the valvehead 26. Inthis mannenyariations in vacuum pressure will affect theoperation of the air bleeder. It shouldalso be noted that theconformation of thevalve head 26 proceeds rather abrupt- 1y from amaximum to a minimum-cross section. The purpose of this latterconstruction is to permit the extremely rapid increase of the effectivesize of the orifice 23 upona slight movement of the valvestem 25. L I

T e..modified form of construction :shownin Fig. 4, which may :bevsubstituted for that shown in Fig. 1,- contemplates; a i snap-actionmode of operation. This form of construction consists the housing 40against the end of-the valve 43.

The discs 45, however, possess an original inherent deformation so thatthe thermostatic de- I formation action or movement must necessarilyovercome such inherent stress before the bimetallic disc itself willassume a different conformation. .The construction of such a bimetallicdisc which is adapted to have a socalled snap-action is thoroughlydescribed in a prior: Patent No. 1,639,708 issued August 23, 1927 toJohn A. Spencer.

A threaded retaining cap 46 is provided inthe upper end of the housing40, similar tothe previously described threaded cap 30. A T-shapedpassage 47, of smaller cross-sectional area than that of the orifice 41is provided in the lower end of the valve 43. The extreme lower end ofthe valve 43 is of a conical or convex'shape as indicated at 48 andadapted to seat 011' the con cave face 49 of the orifice 41.Inoperation, an increase in temperature will not affect the movement ofany of the above described parts, until a certain predeterminedtemperature has been attained. When such predetermined temperature isreached, the bi-metallic discs 45 willthen become deformed with'asnap-action at which time the lower end of the valve 43 =will seat uponthe orifice face 49. In'this manner, it will be seen that a secondandsmaller passage 'or orifice 47 has been-suddenly substituted for theoriginal and larger orifice 41. A decrease in temperature below thepredetermined value will produce an oppositemovement of the parts.

It should also benoted that the 'bi-metallic discs 10, 29 and 45inall-forms of construction are loosely mounted within the-housing'andare not permanently attached thereto, whereby they; will at all timespermit a maximumfreedom ofmovement. Furthermore the entire thermo--static control unit may be cheaply and quickly assembled merely byinserting the valve stem, the spring and the discs and-thenscrewingtheretaining cap'll or 30, as the case may be, into position in thehousing. In'con-nection vwith the constructionsshown in Figs. 2 and4,the relative position of the retaining caps :30 and 46 with respect to.their respective housings-2l and 40 will alsoserve as ameansforwregulating'the initial position of the valve-stem 25 and? foradjustably determining the temeprature at which the orifice 23 will .beopened. q

'The fabrication of the bi-metallic elementsin the. form of discsfurther insures the positive-op eration of the devicev in thatthe-variation; in the co-efficient of expansion between .the two metalswill be concentrated at one .point,,.viz., the center of the disc. Theutilization of bi-jm'etallic discs is particularly desirable in theforms" ofconstruction of the thermostatic control u'nith'ere inbeforedescribed, inasmuch as there is a oertain necessary limitation placedupon the space available for the location of the bi-metallic elements. Qwe Other modes ofapplying' the principle of 'my invention may beemployed instead-of the one explained, change being madeas regards themechanism herein disclosed, provided the means stated by any of thefollowing claims or the equivalent of such stated means be employed.

I therefore particularly point out and distinctly claim as my invention:

1. A device of the character described, comprising a housing memberhaving an exterior screw threaded portion and an interior screw threadedportion, valve means movably mounted in said housing, a screw threadedadjustable member received in said interior screw threaded portion, andthermostatic means comprising a plurality of plates loosely andseparately mounted between said valve means and said adjustable member.

2, A device of the character described, comprising a housing memberhaving an exterior screw threaded portion and an interior screw threadedportion, valve means movably mounted in said housing, a screw threadedadjustable member received in said interior screw threaded portion, andthermostatic means comprising a plurality of plates loosely andseparately mounted between said valve means and said adjustable memberand spring means forcing said valve means against said thermostaticmeans.

3. A device of the character described, comprising a housing memberhaving an exterior screw threaded portion and an interior screw threadedportion, passages leading through said housing member, valve meansmovably mounted in said housing, a valve orifice disposed in saidpassage and in cooperative relationship to said valve means, a screwthreaded adjustable member received in said interior screw threadedportion, and thermostatic means comprising a plurality of plates looselyand separably mounted between said valve means and said adjustablemember.

4. A device for metering a fluid intake orifice of an internalcombustion engine comprising the combination of a housing memberv havingan interior screw threaded portion, an adjustable cap member mountedtherein, pa'ssages leading through said housing member, a movable valvestem mounted in said housing member, a valve orifice disposed in saidpassage and in cooperating relationship to said valve stem, a secondorifice of relatively smaller area than that of said first-named orificepositioned in said valve stem, another passage communicating from saidfirst orifice to said second orifice, and a plurality of thermostaticelements loosely and separably mounted between said valve stem and saidadjustable cap adapted to actuate the valve stem.

WILLIAM H. SHAW.

